Welcome to FlyerTalk. There are five programs which offer transfers to a broad range of airline and hotel partners:
American Express Membership Rewards
Lowest cost card: American Express
Everyday, $0
Transfer
partners: 17 Airlines + 4 Hotels
Chase Ultimate Rewards
Lowest cost card: Sapphire Preferred VISA, $95
Transfer
partners: 6 airlines + 3 Hotels + Amtrak
Diners Club Rewards
Lowest cost card: Diners Club
Premier MasterCard, $95
Transfer
partners: 14 airlines + 7 Hotels + Amtrak
Starwood Preferred Guest
Lowest cost card: SPG American Express, $65
Transfer
partners: 30 Airlines + Redeem at Starwood Hotels + Amtrak
ThankYou Rewards
Lowest cost card: Citi Premier MasterCard, $125
Transfer
partners: 9 airlines + 1 Hotel
Many cards offer a first year waiver of the annual fee. I have listed the fee which would apply after the introductory offer.
If you prefer United Airlines note that only Chase offers cards with 1:1 transfers to Mileage Plus.
American Express and Chase offer a much larger number of card which participate in their rewards program than do the others. This creates more opportunities to earn new card account bonuses over time.